Situated in the left wing of the ground floor, the large rectangular ballroom looks out onto six balconies.
The room is adorned with mirrors set in carved wooden frames with plant motifs. The mirrors were made in Naples in the nineteenth century. The imposing gilt bronze crystal chandeliers were made in France.
A frieze with white heads protruding from a sky-blue background runs along the faux marble walls with twenty-four pilasters surmounted by Corinthian capitals with faux marble panelling.
The lowered vault by Guglielmo Bechi has monochrome decoration and is inspired by the architectural motif in Pompeian baths. A Palladian window separates the ballroom from a smaller room “for the use of the orchestra players” which has pink wax walls.